Document Type thesis Author Name Pugsley, Lisa M URN etd-042612-105703 Title Extraordinary Magnetoresistance in Two and Three Dimensions: Geometrical Optimization Degree MS Department Physics Advisors L. Ramdas Ram-Mohan, Advisor Germano S. Iannacchione, Department Head Padmanabhan K. Aravind, Committee Member Keywords metal-semiconductor structure conductivity extraordinary magnetoresistance nanoscale magnetic sensor Date of Presentation/Defense 2012-04-25 Availability unrestricted
The extraordinary magnetoresistance (EMR) in metal-semiconductor hybrid structures was first demonstrated using a van der Pauw configuration for a circular semiconductor wafer with a concentric metallic inclusion in it. This effect depends on the orbital motion of carriers in an external magnetic field, and the remarkably high magnetoresistance response observed suggests that the geometry of the metallic inclusion can be optimized to significantly enhance the EMR. Here we consider the theory and simulations to achieve this goal by comparing both two-dimensional as well as three-dimensional structures in an external magnetic field to evaluate the EMR in them. Examples of structures that are compatible with present day technological capabilities are given together with their expected responses in terms of EMR. For a 10 micron 2D square structure with a square metallic inclusion, we see a MR up to 10^7 percent for an applied magnetic field of 1 Tesla.
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